Locally applicable information about climate and soil properties can help farmers identify opportunities and reduce risks associated with changing to new land uses. This article describes techniques for preparing high-resolution regional maps and GIS surfaces of agriculturally relevant climate parameters. Ways of combining these climate surfaces with soil data and information about the physical requirements of crops to identify areas likely to be the most suitable for new high-value crops are then outlined. Innovative features include methods for merging observations from temporary climate stations installed for one to two years in conjunction with longer-term climate station observations to improve input data for the maps, and techniques for mapping quantiles of climatic factors that may constrain agricultural operations. Examples are the expected ‘one-in-five year’ first and last frost dates, and the ‘one-in-five year’ lowest and highest seasonal rainfalls. The use of night-time satellite infrared observations to improve spatial resolution of frost hazard maps is also described. Typical standard errors of these climate mapping techniques are summarised. The benefits of ongoing consultation with local farmers and local government staff during the design and implementation of climate/soil/crop potential studies are described. These include optimising products to meet local needs, quality control of the resulting maps and GIS surfaces through local knowledge, and improved uptake of information by users. Further applications of techniques described in this paper include products useful to the energy sector, preparation of daily gridded climate data estimates for use in water quality and plant growth modelling, and development of regional climate change scenarios.

An assimilation of radar reflectivity into a numerical weather prediction (NWP) model with a horizontal resolution of 2.8 km is presented and applied to three severe convective events. The suggested assimilation method takes into account differences between the model and radar-derived precipitation in modifying vertical profiles of water vapour mixing ratio in each model time step by the nudging approach. Version 3.9 of the LM COSMO (Local Model COSMO) – NWP model used in this study includes the explicit formulation of the cloud and rain processes involved. Two variants of the assimilation technique are designed and outputs of their implementation are compared. The first variant makes use of the ground data only, while the second utilises vertical profiles of precipitation water. Both variants provide an improvement of precipitation forecast in comparison with outputs of the control run without assimilation procedures applied. When the assimilated radar data indicate initial precipitation near an expected storm, the NWP model is capable of forecasting basic features of the storm development two to three hours ahead. Three case studies are presented. In one, the assimilation method that takes into account the vertical structure of the precipitation water yields better results than the others which utilise ground data only. However, for the remaining two case studies both types of the assimilation method produce comparable results.

This paper presents an analysis of rainfall amounts in Greece. For this purpose, monthly and annual rainfall data from 36 representative Greek weather stations were analysed statistically. Rainfall is represented by a standardised annual departure calculated as the ratio of the annual departure to the standard departure. The departures were calculated for two regional subdivisions. Clear evidence of changes in Greece's rainfall patterns over the past 25 years were found. The effect of changes on climatological rainfall means (‘normals’) is addressed and possible shifts in the rainy season were investigated. The secular variability of long time-series of annual rainfall amounts was also examined. In addition, the five-year running means of annual and monthly rainfall data and ‘normals’ were plotted. Comparisons of the means from the ‘old’ and ‘new’ 10-, 20- and 30-year, CLINO (Climatological Normal) period 1961–90 (the latest global standard normal period) and from the periods 1900–49 (‘old’ regime) and 1950–99 (‘new’ regime), as well as examination of the secular trend, shows that there is evidence that some parts of Greece have had shifts in their rainfall regime towards drier conditions. In general, rainfall amounts began to decline in the 1980s, a trend which has continued to the present. Most years between 1980 and 1999 experienced below to well-below ‘normal’ rainfall. Discrepancies between the ‘old’ and ‘new’ mean values for the amounts of rainfall and differences in the duration of rainy season suggest that ‘normal’ rainfall data for various water supply, planning, engineering and agricultural national projects should be calculated for the last 30 years. This is mostly true because of indications of a changing climate in Greece, a fact that requires more recent updating of the climatological ‘normals’.

When high pressure is located near the Korean peninsula, a diffluent wind regime generally occurs over the Yellow Sea. At night or early morning, diffluent westerly winds occur on the western side of the Korean peninsula near Inchon city and encounter a combined land breeze and katabatic easterly offshore wind, resulting in conditions ranging from calm to a moderate westerly wind near the coast. Nocturnal radiational cooling of the land surface and the moisture laden westerly winds can cause air near the coast to become saturated, resulting in coastal advection fog. During the day, on the other hand, the synoptic-scale westerly wind is reinforced by a westerly sea breeze and is further reinforced by a westerly valley wind directed upslope towards the mountain top. Even if the resulting intensified onshore wind could transport a large amount of moisture from the sea over the land, it would be very difficult for fog to form because the daytime heat flux from the ground would develop the convective boundary layer inland from Inchon city sufficiently to reduce significantly the moisture content of the air. Therefore, fog does not generally form in situ over the inland coastal basin. When an area of cold sea water (10 °C average) exists approximately 25–50 km offshore and the sea surface temperature increases towards the coast, air parcels over the cool sea surface are cooled sufficiently to saturation, resulting in the formation of advection sea fog. However, at the coast, nocturnal cooling of the ground further cools the advected moist air driven by the westerly wind and causes coastal advection fog to form.

Most operational hail detection algorithms for single-polarisation radars are based on the analysis of the vertical profiles of radar reflectivity. At KNMI (Royal Netherlands Meteorological Institute) and RMI (Royal Meteorological Institute of Belgium) the probability of hail is derived from the height of the freezing level and the 45-dBZ radar echo top height (maximum height of the 45-dBZ echo). Echo tops are affected by errors in the measured reflectivity itself and by errors in the height assigned to these reflectivities. This study investigates the quality of radar echo top heights as a function of range and explores the implications for hail detection.

The method is based on the comparison between reflectivity measurements from two radars on the vertical cross-section extending between these radars. In a first step, sampling errors related to the radar Volume Coverage Patterns are analysed using idealised storm profiles. Subsequently, real reflectivity data for 25 thunderstorm episodes are compared. It is found that the quality of the maximum reflectivity measurements strongly deteriorates with range and that about half of this degradation can be attributed to overshooting effects. Height assignment differences between the two radars are limited to about 0.5 km. Errors on the reflectivity measurements strongly affect the frequency of 45-dBZ threshold exceedances. However, once the threshold is exceeded, errors in measuring the 45-dBZ echo top heights generally affect the derived probability of hail by less than 20%.

The objective of the present study is the calculation of the spatial distribution of sunshine duration in the territory of Slovenia. Four maps at 1 km resolution were prepared to present the spatial distribution of sunshine duration for winter, spring, summer and autumn. The values on all four maps are 30-year mean seasonal sunshine duration, calculated from measurements from 43 meteorological stations in the period 1971–2000. The seasonal presentation was chosen due to the high inter-seasonal variability in spatial distribution of sunshine duration. The values on the maps were calculated on a mathematical horizon, to avoid the influence of geographical, urban and vegetation distortions. The interpolation model is a combination of a multivariate regression model, residual kriging and simple mathematical models. Geographical variables (altitude, latitude and longitude) are used in models to explain the spatial variability of sunshine duration. For each season, regionalisation is performed based on sunshine duration data, derived geographical data and radio-sounding data. The interpolation models are developed for each region separately and afterwards the calculated layers are merged using GIS techniques.

Spanish building legislation has recently changed and now requires an updated and restructured Technical Building Code which is in accordance with European directives. The norm contained in this Code is based on studies of extreme values for climatic elements such as temperature, precipitation and wind. Revised maps of extreme values for climatic elements with a 50-year recurrence interval are required. Here, extreme maximum and minimum temperature maps for Spain are evaluated and mapped by means of geographical information technology. The data are extracted from the historical database held by the Spanish Meteorological Institute. Daily extreme temperatures from 1,181 stations with records going back more than 30 years have been used. The maximum and minimum temperatures are determined as 50-year mean recurrence interval values. To obtain these values, a Gumbel distribution is fitted to the extreme annual values extracted from the database. Spatial interpolation in a regular 5 km × 5 km grid of the annual maximum temperature is made by ordinary kriging. Meanwhile, for the annual minimum temperature a residual kriging has been applied due to its strong dependence on altitude.

Springtime meteorological and satellite data from 1971 to 2000 have been used to assess surface desertification and grassland deterioration to obtain a better understanding of the synoptic characteristics of dust storms observed in Inner Mongolia, the relationship between dust storms and their impact on the Beijing-Tianjin Region, and the effect of climatic change on the surface environment of dust storm source areas in Inner Mongolia. Based on the statistics and the analysis of weather charts during each dust storm event, details and characteristics of sand and dust source regions, such as cold air paths, areas of strong winds and typical synoptic types were obtained. Temperature was found to be the most significant indicator of climate change in the dust storm source regions, having increased by 1.01 °C in the Alxa source region and by 0.96 °C in Hunshdak over the past three decades. Other factors include lack of precipitation, higher evaporation, lower relative humidity, soil desertification and decrease of grasslands in the source regions. As a consequence, nearly two-thirds of the very strong dust storm events observed in Inner Mongolia (characterised by horizontal visibility below 1000 m and wind speeds of 12 m s−1 or over) led to suspended dust or dust storms in the downwind area, the Beijing-Tianjin Region. This study also analyses the upper air and surface weather charts of 58 very strong dust storm events and established the direction of three cold air paths: northwesterly, westerly and northerly. The northwesterly cold air path is seen as the major one, responsible for 58.6% of the dust storm episodes. In addition, the observed areas where strong winds occur lie mostly across the central-west and central regions of Inner Mongolia. Finally, the synoptic situations associated with dust storm events can be classified into three types: trough, northwesterly current and Mongolian vortex. The predominant synoptic system is the trough, responsible for 63.8% of the 58 events analysed in this study.

A forecasting system for fungal infection of turfgrass using weather-based empirical indices (the ‘Fidanza’ and ‘Schumann’ models) was developed and evaluated for its ability to predict the occurrence of brown patch (Rhizoctonia blight) infection episodes at an experimental site in southeastern USA. Disease observations took place at the Turfgrass Field Laboratory in Raleigh, North Carolina between 8 June and 17 August 2003. Three meteorological data sources were used to generate disease risk indices using the empirical models: an on-site observing station, an observing station at a nearby airport, and the US National Weather Service's operational Eta weather forecast model. Visual observations of brown patch activity were conducted in the field and used to evaluate the accuracy of the disease prediction models. Results indicate that the Fidanza and Schumann models correctly predicted brown patch activity on 48% and 30% of the days on which disease occurred, respectively. A diagnosis of the model performance of these disease indices was undertaken. Results are dependent on occurrence of high temperatures and rainfall and independent of the source of the meteorological information (on-site, airport and the Eta model); therefore, regional meteorological information can be effectively applied to develop turfgrass disease forecasting systems. Ongoing efforts are directed towards developing new disease indices and modifying existing indices before an operational disease forecasting system can be implemented.